Publication: 6,7-Diaza-1-methoxy-5-methyl-2,8-dioxabicyclo[3.2.1]oct-6-ene. A Bicyclic Precursor of a Dioxa Carbonyl Ylide and a Dioxacarbene.

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Title	6,7-Diaza-1-methoxy-5-methyl-2,8-dioxabicyclo[3.2.1]oct-6-ene. A Bicyclic Precursor of a Dioxa Carbonyl Ylide and a Dioxacarbene.
Authors/Editors*	Wojciech Czardybon, Wojciech Sokol, John Warkentin, Nick Henry Werstiuk
Where published*	J. Phys. Org. Chem.
How published*	Journal
Year*	2007
Volume	in press
Number
Pages
Publisher
Keywords	bicyclic oxadiazoline, carbene, carbonyl ylide, DMAD, kinetics, DFT calculations
Link	http://www3.interscience.wiley.com/cgi-bin/abstract/117857492/ABSTRACT
Abstract	Synthesis of a bicyclic 2,2-dioxa oxadiazoline (6,7-diaza-1-methoxy-5-methyl-2,8-dioxabicyclo[3.2.1]oct-6-ene) is reported. Its thermolysis at 27Â°C is about 200 times as fast as the thermolysis of a monocyclic oxadiazoline model system. Presumably, a cyclic dioxa carbonyl ylide is formed initially and the ylide then undergoes a bond scission to afford either a dioxacarbene or a dialkylcarbene or it cyclizes to an oxirane. A small fraction of a dialkylcarbene was trapped as the product of addition to dimethyl acetylenedicarboxylate (DMAD). Computations of the barriers to the loss of N2 from the oxadiazolines and to the formation of the carbenes from the carbonyl ylide resulting from thermolysis of the bicyclic oxadiazoline are compared to corresponding barriers for a similar monocyclic oxadiazoline. The rate acceleration is accounted for in terms of geometric factors. The complex products from the decomposition of the bicyclic oxadiazoline were not studied.